Organic electroluminescent element, also referred to as OLED element, receives much concern due to the advantages of self-illumination, rich color, rapid response speed, wide viewing angle, light weight, low thickness, low power consumption, capability of achieving flexible display, etc. Moreover, display devices manufactured by the OLED elements are considered as display devices with significant application prospect.
The basic structure of the OLED element is a sandwich structure formed by an anode, a cathode and an organic functional layer disposed between the anode and the cathode, wherein the organic functional layer generally includes a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), etc. When voltage is applied to the OLED element, holes outputted from the anode and electrons outputted from the cathode are combined in the organic functional layer, so that the organic functional layer can emit light and the light emitted by the organic functional layer is emitted out of the OLED element through the anode or the cathode.
However, after the conventional OLED element is manufactured, the thickness of layers of the OLED element is unchanged, so the optical cavity length of the OLED element is nonadjustable and the wavelength of light emitted by the OLED element is unchanged, namely the light color of the OLED element is also nonadjustable, and hence the display effect of the display device can be poor.